From accurate measurement to identifying treatable secondary causes and establishing evidence-based treatment targets
Accurate diagnosis of hypertension requires more than a single elevated blood pressure reading. The clinical evaluation serves three purposes: confirming that hypertension is real and persistent, excluding secondary causes that may be amenable to targeted treatment, and stratifying cardiovascular risk to guide treatment thresholds and targets.1,2
This module covers the practical clinical framework for achieving all three goals, with particular emphasis on the pharmacological implications of each diagnostic finding. It also introduces the evidence-based framework for treatment targets that informs all subsequent pharmacology modules.
Office technique, out-of-office monitoring, and the four BP phenotypes
Accurate blood pressure measurement is foundational to the diagnosis. Errors in technique are among the most common sources of misclassification, producing both over- and under-diagnosis of hypertension.1
Standard patient preparation requires the patient to be seated quietly for at least five minutes before measurement, with no caffeine, exercise, or smoking within 30 minutes, bladder emptied, back supported, feet flat on the floor, and arm at heart level. Talking during measurement should be avoided.
A validated electronic sphygmomanometer is preferred over the auscultatory method. Cuff sizing is critical: bladder length should be 80% and width 40% of arm circumference. An undersized cuff falsely elevates readings; an oversized cuff may falsely lower them.
Two readings taken one to two minutes apart should be averaged. Both arms should be measured at the initial visit, with the higher reading arm used for subsequent measurements. A difference greater than 15 mmHg between arms warrants vascular evaluation.
An average of at least two readings on at least two separate visits is required to establish a diagnosis. A single elevated reading in a symptomatic patient presenting with a hypertensive emergency may prompt immediate action regardless of confirmation protocol.
Out-of-office blood pressure measurement is increasingly recognized as essential, both for diagnosis and for treatment optimization.2,3
Ambulatory blood pressure monitoring (ABPM) is considered the gold standard for blood pressure diagnosis and phenotyping.3 It provides 24-hour mean, daytime mean, and nighttime mean values. Diagnostic thresholds are a 24-hour mean at or above 130/80 mmHg, daytime mean at or above 135/85 mmHg, and nighttime mean at or above 120/70 mmHg.
ABPM also identifies nocturnal dipping status: a normal nocturnal dip is a fall of 10% or more in nighttime blood pressure. Non-dippers and reverse-dippers carry higher cardiovascular risk independent of daytime blood pressure.3 Among all blood pressure measurement methods, ABPM is the most accurate predictor of cardiovascular outcomes.
Home blood pressure monitoring (HBPM) uses validated automated devices and is patient-performed. The recommended protocol is twice daily, morning and evening, for at least seven days, discarding day one readings and averaging the remainder. The diagnostic threshold is at or above 135/85 mmHg, which is equivalent to an office reading of at or above 140/90 mmHg. HBPM is useful for treatment titration and adherence monitoring.
Four blood pressure phenotypes are defined by the relationship between office and out-of-office measurements.3
| Phenotype | Office BP | Out-of-Office BP | Clinical Significance |
|---|---|---|---|
| Normotension | Normal | Normal | No treatment typically needed |
| White Coat Hypertension | Elevated | Normal | Prevalence ~15–30%; not entirely benign; associated with increased long-term risk of sustained hypertension and modest excess cardiovascular risk |
| Masked Hypertension | Normal | Elevated | Prevalence ~10–15%; carries similar cardiovascular risk to sustained hypertension; detected only with ABPM or HBPM |
| Sustained Hypertension | Elevated | Elevated | Requires treatment |
ABPM or HBPM should be performed before initiating antihypertensive therapy in patients without compelling indications. This avoids unnecessarily treating white coat hypertension, which affects a meaningful proportion of patients with elevated office readings.
History, physical examination, and baseline laboratory workup
A systematic history in the newly diagnosed hypertensive patient addresses four domains. The first covers duration and prior measurements: when hypertension was first detected, whether prior readings are available, any history of hypertension in pregnancy, and any history of childhood kidney disease or urinary tract infections.
The second domain addresses symptoms suggesting secondary causes. Episodic headache, diaphoresis, and palpitations suggest pheochromocytoma. Muscle weakness, polyuria, and nocturia suggest primary aldosteronism. Weight gain, easy bruising, and proximal myopathy suggest Cushing syndrome. Snoring, witnessed apneas, and daytime somnolence suggest obstructive sleep apnea. Flank pain, hematuria, or a family history of renal cysts suggests renal parenchymal disease.
The third domain covers cardiovascular risk factors and target organ damage symptoms: chest pain, dyspnea, and orthopnea for cardiac involvement; transient neurological symptoms for cerebrovascular disease; claudication and cold extremities for peripheral vascular disease; polyuria and nocturia for renal impairment; and visual disturbance for retinopathy.
The fourth domain covers medications and lifestyle. All prescription and over-the-counter medications, supplements, and recreational drugs should be reviewed. Particular attention is warranted for NSAIDs (non-steroidal anti-inflammatory drugs), oral contraceptives, decongestants, stimulants, calcineurin inhibitors, erythropoietin, venlafaxine, and monoamine oxidase (MAO) inhibitors. Dietary sodium intake, alcohol consumption, physical activity, and tobacco use should also be documented.
A focused but thorough examination is essential.1 Vital signs should include blood pressure in both arms while seated, repeated after two minutes of standing in elderly patients to evaluate for orthostatic hypotension, along with heart rate, respiratory rate, body mass index, and waist circumference.
The cardiovascular examination includes auscultation for a third or fourth heart sound suggesting volume overload or left ventricular hypertrophy (LVH), an abdominal bruit suggesting renovascular disease, radio-femoral delay or diminished femoral pulses suggesting coarctation, and peripheral pulse assessment.
Fundoscopic examination provides direct visualization of hypertensive target organ damage. Arteriovenous nicking and copper or silver wiring indicate chronic hypertension. Flame hemorrhages, cotton-wool spots, and papilledema indicate severe or malignant hypertension. Grade III or IV retinopathy warrants urgent blood pressure management.
Signs of secondary causes include moon facies, buffalo hump, abdominal striae, and proximal muscle weakness in Cushing syndrome; thyroid enlargement or signs of thyroid dysfunction; neck or abdominal bruits in renovascular disease; and neurofibromas or café-au-lait spots suggesting pheochromocytoma associated with neurofibromatosis type 1 (NF1).
Signs of target organ damage include a laterally displaced apex beat or fourth heart sound indicating left ventricular hypertrophy, neurological deficits from prior stroke, and peripheral edema from heart failure or renal disease.
Recommended baseline workup for all hypertensive patients includes urinalysis with microscopy, a basic metabolic panel, lipid panel, complete blood count, electrocardiogram, and thyroid-stimulating hormone (TSH).1,2
Urinalysis is examined for proteinuria suggesting hypertensive nephrosclerosis or primary renal disease, hematuria suggesting glomerulonephritis or renovascular disease, and casts indicating intrinsic renal disease. The basic metabolic panel provides serum creatinine and estimated glomerular filtration rate (eGFR) for CKD staging, electrolytes including potassium (hypokalemia raises suspicion for primary aldosteronism; hyperkalemia is a risk with renin-angiotensin-aldosterone system (RAAS) inhibitors in CKD), and glucose for diabetes and metabolic syndrome.
The lipid panel enables atherosclerotic cardiovascular disease (ASCVD) risk calculation. The electrocardiogram is examined for LVH by voltage criteria, arrhythmias, and evidence of prior myocardial infarction.
Additional testing is ordered based on clinical suspicion: an aldosterone-to-renin ratio for primary aldosteronism, plasma metanephrines for pheochromocytoma, renal artery imaging for renovascular hypertension, 24-hour urinary free cortisol or overnight dexamethasone suppression test for Cushing syndrome, polysomnography for obstructive sleep apnea, and echocardiography when LVH is suspected or cardiac function assessment is needed.
Identifying and managing treatable secondary causes
Secondary hypertension accounts for 5–10% of all hypertension cases but is disproportionately represented among patients with resistant hypertension, where it may account for 30–40% of truly resistant cases.4 Identifying secondary causes matters for three reasons: specific etiologic treatment may achieve cure or marked improvement; standard antihypertensive regimens are often partially or fully ineffective unless the underlying cause is addressed; and some secondary causes carry independent cardiovascular risk.
Clinical clues warranting secondary evaluation include onset of hypertension before age 30 without family history or obesity, resistant hypertension uncontrolled on three or more agents including a diuretic, sudden worsening of previously controlled hypertension, hypokalemia not explained by diuretic use, an abdominal or flank bruit, episodic symptoms of headache, diaphoresis, and palpitations, and onset or worsening associated with a new medication.
Reduced nephron mass leads to sodium and water retention, RAAS activation, and impaired pressure-natriuresis. Failing kidneys also fail to suppress renin adequately, perpetuating both volume-dependent and renin-dependent hypertension.5
Evaluation includes eGFR, urinalysis with microscopy, spot urine albumin-to-creatinine ratio, and renal ultrasound assessing size, echogenicity, symmetry, and cysts. RAAS inhibitors, either an ACE inhibitor or an angiotensin receptor blocker (ARB), are first-line for hypertension in CKD with proteinuria, based on demonstrated renoprotective effects beyond blood pressure lowering.5 Loop diuretics are preferred over thiazides when eGFR falls below 30 mL/min/1.73m². A rise in creatinine of up to 30% after RAAS inhibitor initiation is acceptable and expected; greater rises or hyperkalemia warrant dose reduction or discontinuation. Full pharmacological management of CKD-related hypertension is addressed in HTN-07.
Renal artery stenosis (RAS) reduces perfusion pressure distal to the stenosis, activating the juxtaglomerular apparatus and driving renin-dependent hypertension. In bilateral RAS or stenosis to a solitary kidney, RAAS inhibition reduces glomerular filtration rate precipitously by removing the angiotensin II-mediated efferent arteriolar vasoconstriction that maintains intraglomerular pressure.4
Atherosclerotic RAS affects elderly patients with multiple cardiovascular risk factors, typically producing ostial lesions that may be progressive. Fibromuscular dysplasia (FMD) affects young to middle-aged women, produces non-ostial mid or distal renal artery changes with a classic "string of beads" appearance on imaging, and is generally non-progressive.
Evaluation begins with Doppler renal artery ultrasound as a non-invasive first-line screen, followed by computed tomography angiography or magnetic resonance angiography for high sensitivity and specificity. Catheter-based renal arteriography is the gold standard and is performed when intervention is planned.
For FMD-related RAS, percutaneous transluminal angioplasty is often curative; drug therapy serves as a bridge or adjunct. For atherosclerotic RAS, medical therapy with risk factor modification and RAAS inhibition is generally preferred. The ASTRAL and CORAL trials demonstrated no benefit of renal artery stenting over optimal medical therapy in most patients.6,6b ACE inhibitors and ARBs are contraindicated or used with extreme caution in bilateral RAS or stenosis to a solitary kidney; alternative agents such as calcium channel blockers (CCBs), diuretics, or centrally acting agents are preferred in these circumstances.
Primary aldosteronism (PA) is the most common endocrine cause and the most common surgically correctable cause of hypertension, affecting an estimated 5–10% of all hypertensive patients and up to 20% of those with resistant hypertension.7 Unilateral aldosterone-producing adenoma (APA) accounts for approximately 35% of cases and is potentially surgically curable. Bilateral adrenal hyperplasia (BAH) accounts for approximately 60% and is treated medically.
Screening uses the aldosterone-to-renin ratio (ARR) measured under standardized conditions. An ARR above 20–30 (ng/dL)/(ng/mL/hr) is suspicious; an ARR above 30 with aldosterone above 15 ng/dL is highly suggestive.7 Confirmatory testing uses oral sodium loading with 24-hour urine aldosterone measurement, or an intravenous saline infusion test. Adrenal CT is performed first for subtype differentiation, but adrenal vein sampling (AVS) is required in most patients before surgery, as CT has an approximately 40% error rate in distinguishing APA from BAH.
For confirmed PA with a surgical candidate and APA, adrenalectomy is the treatment of choice, with perioperative spironolactone to prepare the contralateral adrenal. For BAH or non-surgical candidates, mineralocorticoid receptor antagonists (MRAs) are the etiologic pharmacological treatment. Spironolactone is initiated at 12.5–25 mg per day and titrated to 100–400 mg per day; it is the most potent MRA but is non-selective, with anti-androgenic adverse effects. Eplerenone is a selective MRA with fewer off-target effects, dosed at 25–50 mg twice daily, and is preferred in men concerned about gynecomastia or sexual dysfunction. Potassium should be monitored closely, particularly when CKD coexists. Thiazide monotherapy should be avoided as it worsens hypokalemia.
Pheochromocytoma (adrenal) and paraganglioma (extra-adrenal) are catecholamine-secreting tumors. Though they affect fewer than 1% of hypertensive patients, they carry significant cardiovascular risk and are potentially surgically curable.4
The classic presentation is a triad of paroxysmal headache, diaphoresis, and palpitations. Hypertension may be paroxysmal or sustained, and episodes may be triggered by physical pressure on the tumor, anesthesia induction, or certain drugs including opioids, metoclopramide, tyramine, and glucagon. Associated hereditary syndromes include multiple endocrine neoplasia (MEN) 2A and 2B, von Hippel-Lindau disease, neurofibromatosis type 1, and succinate dehydrogenase (SDH) gene mutations causing paraganglioma syndromes.
Plasma free metanephrines have the highest sensitivity at approximately 99% and are the preferred initial biochemical test.4 Catecholamines are secreted episodically, but their metabolites, specifically metanephrines, are produced continuously within the tumor and provide a more reliable biochemical signal. Imaging with CT or MRI of the abdomen and pelvis follows biochemical confirmation. Functional imaging with metaiodobenzylguanidine (MIBG) scintigraphy or Ga-68 DOTATATE PET-CT is used for metastatic or extra-adrenal disease.
Alpha-adrenoceptor blockade must be established before beta-blockade in pheochromocytoma. Initiating a beta-blocker first removes beta-2-mediated vasodilation while leaving alpha-1 vasoconstriction unopposed, which may precipitate a severe or fatal hypertensive crisis. Phenoxybenzamine (non-selective, irreversible) or doxazosin (selective alpha-1, reversible) is started 10–14 days before surgery. Beta-blockade for rate control is added only after adequate alpha-blockade is confirmed.
Excess cortisol produces hypertension through several mechanisms: activation of mineralocorticoid receptors (cortisol has intrinsic mineralocorticoid activity at high concentrations), potentiation of vascular angiotensin II sensitivity, increased hepatic angiotensinogen production, and sympathetic nervous system stimulation.4
The most common cause overall is iatrogenic Cushing syndrome from exogenous glucocorticoids. Endogenous causes include pituitary adenoma (Cushing disease, approximately 70%), adrenal adenoma or carcinoma, and ectopic ACTH (adrenocorticotropic hormone) production from small cell lung cancer or carcinoids. Screening is performed with a 1 mg overnight dexamethasone suppression test, 24-hour urinary free cortisol, or late-night salivary cortisol.
Hypertension caused by iatrogenic Cushing syndrome resolves with glucocorticoid tapering when clinically feasible. For endogenous Cushing syndrome, treating the underlying cause is the priority. Bridge therapy while awaiting definitive treatment includes metyrapone (an 11-beta-hydroxylase inhibitor), ketoconazole (a cytochrome P450 enzyme inhibitor), mifepristone (a glucocorticoid receptor antagonist), or pasireotide for Cushing disease. Standard antihypertensives are used as adjuncts; spironolactone is particularly useful given the mineralocorticoid excess component.
Repetitive nocturnal hypoxemia triggers sympathetic activation, RAAS upregulation, aldosterone excess, endothelial dysfunction, and impaired baroreceptor sensitivity.8 Obstructive sleep apnea (OSA) is present in approximately 30–40% of hypertensive patients and up to 80% of patients with resistant hypertension.8
Evaluation begins with the Berlin Questionnaire or STOP-BANG (a validated symptom-based screening questionnaire) screening tool, followed by polysomnography for confirmation or home sleep testing in appropriate patients. CPAP therapy lowers blood pressure by approximately 2–3 mmHg systolic on average, with greater effects in patients with more severe OSA and in those with resistant hypertension.8 Drug therapy with standard antihypertensives remains necessary even with effective CPAP. Mineralocorticoid receptor antagonists are particularly effective in OSA-associated resistant hypertension due to concurrent aldosterone excess.8 Agents that worsen OSA, including opioids and benzodiazepines, should be avoided.
Drug-induced hypertension is common and frequently overlooked. A complete medication history including over-the-counter drugs, supplements, and recreational drugs is essential.1,2
NSAIDs, including cyclooxygenase-2 (COX-2) inhibitors, inhibit renal prostaglandin synthesis. This reduces afferent arteriolar vasodilation, promotes sodium retention, and antagonizes the natriuretic effects of diuretics and RAAS inhibitors. The average blood pressure rise is 3–5 mmHg but may be greater in elderly patients, those with CKD, or those already taking diuretics.
Estrogen-containing oral contraceptives increase hepatic angiotensinogen production, activating the RAAS. Overt hypertension develops in approximately 5% of users and is reversible on discontinuation.
Calcineurin inhibitors, including cyclosporine and tacrolimus, cause renal afferent arteriolar vasoconstriction, sympathetic activation, endothelin upregulation, and sodium retention. Hypertension is highly prevalent in transplant recipients. Amlodipine is the preferred antihypertensive in this population, as it may mitigate calcineurin inhibitor nephrotoxicity. Diltiazem and verapamil should be avoided because they inhibit cytochrome P450 3A4 (CYP3A4) and raise calcineurin inhibitor levels substantially.
Sympathomimetics including decongestants, amphetamines, and cocaine cause hypertension through alpha-1 agonism and, in the case of cocaine, norepinephrine reuptake blockade. Cocaine-associated hypertensive crisis should be treated with phentolamine or benzodiazepines; beta-blockers are contraindicated as they leave alpha-adrenergic vasoconstriction unopposed. VEGF (vascular endothelial growth factor) inhibitors such as bevacizumab reduce nitric oxide production and cause hypertension in up to 30% of oncology patients; CCBs and RAAS inhibitors are commonly used in this setting.
When to initiate therapy, landmark trials, and population-specific targets
The decision to initiate antihypertensive drug therapy is based on both blood pressure stage and total cardiovascular risk.1,2 For Stage 1 hypertension (130–139/80–89 mmHg), pharmacotherapy is indicated when the 10-year ASCVD risk is at or above 10%, or when established cardiovascular disease, CKD, or diabetes mellitus is present. Lifestyle modification alone is appropriate when the 10-year ASCVD risk is below 10% and no high-risk features are present, with reassessment in three to six months.
For Stage 2 hypertension (at or above 140/90 mmHg), pharmacotherapy is recommended for all patients, typically with combination therapy from the outset when blood pressure is at or above 160/100 mmHg. Very high-risk patients with established cardiovascular disease, CKD, or diabetes have a lower threshold for pharmacotherapy and more aggressive blood pressure targets.
Lifestyle modifications should accompany pharmacotherapy at all stages. The DASH diet may reduce systolic blood pressure by approximately 11 mmHg in hypertensive patients.9 Sodium restriction below 2.3 g per day may reduce systolic blood pressure by 5–6 mmHg.9 Each kilogram of weight reduction lowers systolic blood pressure by approximately 1 mmHg, and 90–150 minutes of aerobic exercise per week may reduce systolic blood pressure by 5–8 mmHg.9
The 2017 ACC/AHA guidelines recommend a target below 130/80 mmHg for patients with established cardiovascular disease or a 10-year ASCVD risk at or above 10%, and consider this target reasonable for most other adults.1
The SPRINT trial (2015) compared an intensive systolic target below 120 mmHg against a standard target below 140 mmHg.10 The intensive group had a 25% reduction in composite cardiovascular events and a 27% reduction in all-cause mortality. An important caveat: SPRINT used automated unattended blood pressure measurement, which yields readings approximately 5–10 mmHg lower than standard office measurement. The "120 mmHg" target in SPRINT approximates approximately 130 mmHg by standard measurement technique. The trial excluded patients with diabetes and prior stroke.
The ACCORD trial (2010) compared an intensive systolic target below 120 mmHg against a standard target below 140 mmHg in patients with type 2 diabetes.11 No significant reduction in the primary cardiovascular endpoint was observed with intensive control. A reduction in stroke was seen, but the overall result influenced the recommendation for a target below 130 mmHg rather than below 120 mmHg in patients with diabetes.
The selection of antihypertensive agents is guided by compelling indications, contraindications, comorbid conditions, patient-specific factors, and hemodynamic profile.1,2 The four cornerstone drug classes for primary hypertension management are ACE inhibitors, ARBs, CCBs, and thiazide and thiazide-like diuretics. These classes have the strongest evidence base for reducing cardiovascular morbidity and mortality and form the basis of initial therapy and combination regimens for most patients.1,12
Beta-blockers, alpha-blockers, and other agents occupy specific niches discussed in HTN-05. A full evidence-based treatment algorithm, combination strategies, and management of resistant hypertension are presented in HTN-06.